JP3763634B2 - Bushing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bushing having a cooling fin on a terminal in oil, and more particularly to a technique for suppressing the heat generation of the terminal part in oil by energization of the bushing and improving the cooling effect.
[0002]
[Prior art]
The configuration of the conventional bushing will be described with reference to FIG.
The bushing 1 is used in a lead portion of an electric device such as a transformer, and the electric current sent from the outside passes through the central conductor 3 and then passes through a connecting conductor such as 4 to illustrate the electric device. The main unit is energized. Here, the bushing 1 has a terminal 5 in oil as a seat for connecting the connection conductor 4 to the center conductor 3. The in-oil terminal 5 has several configurations depending on the type of bushing. Here, an in-oil terminal made of a material such as a solid round bar will be described. As a material for the solid round bar conductor, copper having a low resistivity is preferable, but a conductive aluminum material is generally used because the mass is too heavy for installation in an electric device. In addition, since the energization current is substantially proportional to the cross-sectional area of the conductor, such a conductor made of a solid material is applied to a bushing having a high rated current. However, current is difficult to flow inside the conductor due to the skin effect, and mainly flows outside, so current concentration tends to occur at the periphery of the conductor, and a high temperature is generated around the concentrated portion, resulting in an electrical resistance value. Rises. Therefore, when a large current is passed, it is not necessary to simply increase the diameter of the conductor, but it is more effective to increase the surface area of the energizing portion so that heat can be diffused outside the conductor. In other words, the larger the surface area of the conductive material, the more heat diffusion is achieved and the electric resistance value is kept constant, so that the quality of the bushing is improved. In particular, as shown in FIG. 4, in the vicinity of the connection portion between the in-oil terminal 5 a and the connection conductor 4 that connects the electrical equipment, the current 6 flowing through the in-oil terminal 5 a is concentrated to shift to the connection conductor 4. Therefore, it is conceivable that the temperature rises significantly.
[0003]
Therefore, as shown in FIG. 4, heat is diffused by adopting a configuration in which a groove is formed in the oil-in-terminal 5a and the surface area is increased by providing slit-like cooling fins 7a. In such a case, as shown in FIG. 4, the cooling fins are dug into the gaps of the connecting portions as much as possible, and the primary focus is on ensuring the surface area for cooling, and a uniform high position so that the surface area can be fully filled. The groove of the cooling fin 7a is formed.
[0004]
Moreover, the block diagram which looked at the bushing at the time of providing this cooling fin 7a from the lower side is shown in FIG. If the skin effect of the current is taken into consideration in this drawing, it is considered that if the groove is formed in the outer peripheral edge portion of the in-oil terminal 5a, the current flow may be hindered. Since it concentrates in the vicinity, this problem does not occur unless a groove is formed in the connection conductor 4 itself.
Further, the bottom surface of the groove of the conventional cooling fin has a shape processed into a surface having a constant horizontal height as shown in FIG. 6 for ease of processing.
[0005]
[Problems to be solved by the invention]
However, in the configuration in which the grooves of the cooling fins 7a of the in-oil terminal 5a as shown in FIG. 4 are provided at a uniform high position, the conductivity is not taken into consideration until the connection between the in-oil terminal 5a and the connecting conductor 4 is reached. Since it was processed, there was a problem that the energization path of the current 6 to which the cooling fins 7a migrated was narrowed and a sufficient energization path could not be secured. Even if this is not the case, the current has a property that only the surface layer flows because of the skin effect, and current concentration is likely to be caused. However, in the portion where the current at the connection portion between the oil-in-terminal 5a and the connection conductor 4 is concentrated, A surge could be caused that could significantly reduce the quality of the bushing. What can be considered there is a method of reducing the number of cooling fins 7a of the in-oil terminal 5a to ensure a current-carrying path, but the surface area of the in-oil terminal 5a is reduced as the cooling fins 7a are decreased. If it is as it is, there exists a possibility that the cooling effect by the cooling fin 7a may fall.
[0006]
Further, in the groove structure in which the cooling fin as shown in FIG. 6 is processed horizontally, the oil liquid 8 circulating in the transformer tank flows along the groove wall surface of the cooling fin 7a to the bottom surface of the groove. Since there is no escape path, the oil flow 8 is stagnated near the bottom of the groove, and the oil that has received heat from the in-oil terminal 5a and has reached a high temperature does not leave the vicinity of the in-oil terminal. As a result, there is a problem that the cooling effect by the oil flow cannot be expected so much.
[0007]
The present invention has been proposed in order to solve the above-described problems of the prior art, and the object thereof is to provide a simple improvement in the structure of the cooling fins of the bushing oil-in-terminal, so that the in-oil terminal portion is provided. An object of the present invention is to provide a bushing that can prevent heat generation in the vicinity and improve cooling efficiency.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, as the invention according to claim 1, a conductor made of a solid material, a connection conductor fastened to the conductor and connected to the electric device main body, And a cooling fin configured by forming a plurality of grooves in the conductor from below, the groove forming the cooling fin is formed with the shallowest groove in the vicinity of the connection conductor, and the center of the conductor The bushing is characterized in that the individual grooves are formed deeper in stages toward the head.
[0009]
By adopting such a configuration, the cooling efficiency can be improved without hindering the flow of current.
Further, in the present invention, as a second aspect of the present invention, a conductor made of a solid material, a connection conductor fastened to the conductor and connected to the electric device main body, and a plurality of conductors from below are connected to the conductor. A bushing comprising a cooling fin configured by forming a groove, wherein each groove configuring the cooling fin has a groove bottom surface formed in an inclined shape in the groove bottom end direction. Provide a bushing.
[0010]
By adopting such a configuration, when the oil having a high temperature in the cooling fin rises, it can flow to the outside of the cooling fin without staying.
According to a third aspect of the present invention, there is provided the bushing according to the second aspect, wherein the bottom surface of the groove is shallowest at a central portion and becomes deeper toward both end portions.
[0011]
By adopting such a configuration, it is possible to control the oil flow direction of the oil that has reached a high temperature in the cooling fin.
Further, in the present invention, the invention according to claim 4 includes a conductor made of a solid material, a connection conductor fastened to the conductor and connected to the main body of the electric device, and a plurality of the conductors from below. In the bushing provided with the cooling fin formed by forming the groove, the groove constituting the cooling fin is formed with the shallowest groove in the vicinity of the connection conductor, and each groove is formed toward the conductor center. A bushing characterized in that it is formed deep in stages, and each groove has a bottom surface formed in an inclined shape in the direction of both ends of the groove bottom.
[0012]
By adopting such a configuration, the cooling efficiency can be further improved in combination with the above-described operation.
According to a fifth aspect of the present invention, there is provided the bushing according to the fourth aspect, wherein the conductor uses an aluminum alloy having excellent mechanical strength characteristics.
By adopting such a configuration, it is possible to improve the mechanical strength without greatly impairing the cooling efficiency.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a bushing according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same part as the conventional structure, and description is abbreviate | omitted.
In the first embodiment shown in FIG. 1, the cooling fins 7b of the in-oil terminal 5b of the bushing are provided stepwise. That is, the depth of the configured groove is changed stepwise. The main current flow 6 flows from the oil-in-terminal 5b to the connection conductor 4 as shown in FIG. 1, and the structure of the cooling fin 7b leaves a portion along this flow and uses the portion deviated from the main flow for cooling. Fin grooves are formed. By adopting such a configuration, the surface area of the oil-in-terminal 5b is not so different from the surface area of the conventional oil-in-terminal, so that the cooling performance can be expected to be equivalent to that of the conventional product, resulting in an abnormal increase in electrical resistance. Can be prevented. In addition, since sufficient energization paths are taken, temperature rise due to current concentration can be reliably mitigated.
[0014]
In the second embodiment shown in FIG. 2, the bottom surface of the cooling fin, which has been processed horizontally in the past, is inclined from the center toward both ends. It is possible to guide a constant flow to the peripheral portion in FIG. For this reason, the oil that has received heat from the in-oil terminal 5b and has reached a high temperature flows up to the outside of the in-oil terminal 5b by rising due to buoyancy, and the oil having a lower temperature is circulated and changed. It flows into the groove of the cooling fin 7b. Thus, since the oil flow is performed for lubrication, the temperature rise of the terminal in oil is reduced.
[0015]
Further, accompanying the adoption of the above-described embodiment, a structural aluminum material (for example, an aluminum alloy) in which the central conductor of the bushing has mechanical strength can be used. Therefore, since the strength against vibration of the cooling fins is improved, the thickness of the cooling fins can be reduced and the number of fins can be increased. Although the structural aluminum material is excellent in mechanical strength, it has a property inferior in electrical conductivity. However, if the above-described embodiment is adopted, some poor electrical conductivity can be covered.
[0016]
【The invention's effect】
As described above, according to the present invention, the bushing capable of preventing the heat generation in the terminal part in oil by improving the energization characteristics while maintaining the cooling effect of the terminal in oil and further increasing the cooling effect. Can be provided.
[Brief description of the drawings]
FIG. 1 is a structural diagram of an in-oil terminal of a bushing according to a first embodiment of the present invention.
FIG. 2 is a structural diagram of a bottom surface of a cooling fin groove of a terminal in oil according to a second embodiment of the present invention.
FIG. 3 is a structural diagram of the entire conventional bushing.
FIG. 4 is a structural diagram of a conventional bushing bushing in oil.
FIG. 5 is a view showing cooling fins configured on terminals in oil when the bushing is viewed from below.
FIG. 6 is a structural view of a bottom surface of a cooling fin groove of a conventional terminal in oil.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Bushing, 3 ... Center conductor, 4 ... Connection conductor, 7a, 7b ... Cooling fin.

Claims (5)

A conductor made of a solid material, a connection conductor that is fastened to the conductor and connected to the main body of the electric device, and a cooling fin that is formed by forming a plurality of grooves in the conductor from below. The bushing according to the present invention is characterized in that the groove constituting the cooling fin is formed such that the groove in the vicinity of the connection conductor is the shallowest, and each groove is formed deeper in stages toward the conductor center. . A conductor made of a solid material, a connection conductor that is fastened to the conductor and connected to the main body of the electric device, and a cooling fin that is formed by forming a plurality of grooves in the conductor from below. The bushing according to claim 1, wherein each of the grooves constituting the cooling fin has a groove bottom surface formed in an inclined shape in the groove bottom surface end direction. 3. The bushing according to claim 2, wherein the bottom surface of the groove is shallowest at a central portion and becomes deeper toward both ends. A conductor made of a solid material, a connection conductor that is fastened to the conductor and connected to the main body of the electric device, and a cooling fin that is formed by forming a plurality of grooves in the conductor from below. In the provided bushing, the grooves constituting the cooling fins are formed such that the grooves in the vicinity of the connection conductor are the shallowest, and the individual grooves are formed stepwise deeper toward the conductor center. A bushing wherein the bottom surface of the groove is formed in an inclined shape in the direction of both ends of the groove bottom. The bushing according to claim 4, wherein the conductor is an aluminum alloy having excellent mechanical strength characteristics.

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